04/01/2026
When people talk about knee stability, they zoom in on quads and hamstrings.
Important, yes.
But the calves are the quiet stabilisers no one talks about.
If your knee doesn’t trust the ground, it’s often a calf + ankle problem, not a quad problem.
🎊🌲Between Christmas and the beginning of the new year, we traditionally publish our ‘Best of’ series featuring the most influential posts of the year that is coming to an end.
📣 Today 🥇 # rank 8 in 2025
𝗜𝘀 𝗶𝘁 𝗮𝗹𝗹 𝗔𝗯𝗼𝘂𝘁 𝘁𝗵𝗲 𝗤𝘂𝗮𝗱𝘀? 𝗜𝗺𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻𝘀 𝗼𝗳 𝘁𝗵𝗲 𝗖𝗮𝗹𝗳 𝗠𝘂𝘀𝗰𝘂𝗹𝗮𝘁𝘂𝗿𝗲 𝗣𝗼𝘀𝘁-𝗔𝗖𝗟 𝗜𝗻𝗷𝘂𝗿𝘆 𝗶𝗻 𝗥𝗲𝘁𝘂𝗿𝗻 𝘁𝗼 𝗦𝗽𝗼𝗿𝘁 𝗥𝗲𝗵𝗮𝗯
✅ ACL injuries are common in sports involving pivoting and cutting, requiring lengthy rehabilitation. Only 55–65% of athletes return to their pre-injury performance level, and 20% experience a second ACL injury (Ardern et al., 2014; Wiggins et al., 2016). Current rehabilitation guidelines focus on quadriceps and hamstring strength but rarely address the calf muscles, despite their role in knee stability (Andrade et al., 2020).
📘A clinical commentary by Christman and Jayaseelan (2025) explores the role of the calf muscles (gastrocnemius and soleus) after anterior cruciate ligament (ACL) injury and reconstruction (ACLR). It highlights their overlooked contributions to rehabilitation and returning to sports, examining how these muscles affect knee movement, changes after ACL injury, and rehabilitation strategies to reduce re-injury risk. (https://pubmed.ncbi.nlm.nih.gov/40469647/)
🦵 In healthy knees, the soleus helps pull the tibia backward, supporting the ACL, with forces about 28–32% of the hamstrings’ contribution during activities like single-leg landings. The gastrocnemius, however, pulls the tibia forward, similar to the quadriceps, and can stress the ACL (Mokhtarzadeh et al., 2013; Maniar et al., 2022, picture). These muscles also help control knee rotation, with the medial gastrocnemius resisting knee valgus (Maniar et al., 2020). Women have a larger soleus attachment to the tibia, potentially relying more on it for knee stability, but their gastrocnemius produces less force, which may increase ACL injury risk (Edama et al., 2017; Deng et al., 2021).
🦶In ACL-deficient (ACLD) knees, the medial gastrocnemius activates earlier with decreased overall gastrocnemius electromyography (EMG) amplitude, leading to increased knee instability (Lass et al., 1991; Sharifi et al., 2021). The soleus shows reduced activity during walking but increased activity during dynamic tasks, possibly compensating for instability (Hurd & Snyder-Mackler, 2007; Konishi et al., 2020). These changes highlight the need to assess and strengthen calf muscles, aiming for at least 90% strength symmetry with the uninjured leg (Grindem et al., 2015).
🦶After ACLR, research on calf muscles is limited. The soleus shows reduced activity 12–24 months post-surgery during single-leg hops, despite faster reaction times, which could increase the risk of secondary injuries like Achilles tendon rupture (Sritharan et al., 2020; Rhim et al., 2020). Gastrocnemius activity is also reduced during landings, increasing reliance on passive structures like ligaments, which may strain the knee (Dashti Rostami et al., 2018; Vairo et al., 2008). Prolonged gastrocnemius activation after landing may further stress the knee (Nyland et al., 2010). Changes in ankle movement, such as less dorsiflexion and more plantarflexion, suggest athletes may rely more on their ankles to compensate for knee weaknesses (Gokeler et al., 2010; Sharafoddin-Shirazi et al., 2020). Increasing reliance on calf musculature may increase the risk of inhury to not only the knee joint, but also calf musculature.
🏋️♀️Rehabilitation should address these issues early (weeks 1–6) with techniques like electrical stimulation, blood flow restriction, and biofeedback to prevent calf muscle weakness and atrophy (Norte et al., 2021; Charles et al., 2020).
🏋️♂️From week 7 onward, focus shifts to strength training (67–85% of maximum weight), eccentric exercises, and plyometrics to restore calf power, targeting at least 90% symmetry with the uninjured leg (Haff & Triplett, 2015; Barber-Westin & Noyes, 2011). Movement retraining using video feedback and complex sports scenarios to balance ankle dominant movement patterns are recommended (Chua et al., 2021).
👩🦰 Women’s higher ACL injury risk may be worsened by soleus weakness, so targeted calf strengthening is crucial (Ryman Augustsson & Ageberg, 2017). Future research should explore calf-specific exercises, the impact of different surgical grafts, and optimal strength ratios between calf, hamstring, and quadriceps muscles to improve return-to-sport outcomes.
💡In conclusion, the calf muscles play a vital role in knee stability after ACL injury but are often ignored in rehabilitation. Adding calf-focused assessments and exercises could lower re-injury rates and boost return-to-sport success, calling for more research.
📒 References
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